Apparatus for shaping fan blades



Sept. 19, 1950 w. N. L uRcoTT APPARATUS FOR SHAPING FAN BLADES 4 Sheets-Sheet l Filed Aug. 27, 1946 INVENTOR. W/NF/QED N. LU/QCOTT ATrofP/vfy W. N. LURCOTT APPARATUS FOR SHAPING FAN BLADES spf. 19, 1950 v4 sheets-sheet 2 Filed Aug. 27, 194e INVENTOR. l/l//lV-/QDA lV. LURCOTT @ONM A T TOR/VEV Sept. 19, 1950 w. N. LURcoTT APPARATUS FOR sHAPING FAN BLADES 4 Sheets-Sheet 3 *Filed Aug. 27, 194e WBV @www Sept. 19, 1950 w. N. LuRcoTT 2,522,583

APPARATUS FOR SHAPING FAN BLADES Filed Aug. 27, 1946 4 Sheets-Sheet 4 WINF'RED N. LURCOTT ATToRmNiY Patented Sept. 19, 1950 UNITED STATES PATENT OFFICE 2,522,683 APPARATUS Fort' sHAPING FAN BLADES Winfred N. Lurcott, Elizabeth, J., assignor to L. J. Wing Manufacturing Co., New York; N. Y., a corporation of New York Application August 27, 1946, serial No. `693,203

('Cl. 153-3-".\)v

2 Claims. l

The present invention relates to an apparatus for shaping fan blades from a relatively iiat sheet of metal.

In my co-pending application, which is a division of the within application, I have described and illustrated a method and apparatus that may be used for constructing the core and dies utilized in the power press, which is the subject matter of the present invention.

With the apparatus here contemplated, there may be produced on a production scale fan blades, which are hollow and made from metal, with comparatively unskilled labor and each of which blades has the same selected dimensions and operating characteristics.

The present invention contemplates the provision of an apparatus having a core around which the metal fan blade is formed and which core has imparted to it a compound motion whereby the core is lowered from normal position into a position against the sheet of metal and raised from this lowered position back to the normal position.

The present invention further contemplates the provision of a fan blade forming an apparatus having a pair of blade forming dies and the means for counterbalancing the Weight of each die.

The present invention still further contemplates the provision of a fan blade forming apparatus having a pair of'blade forming dies and the means for selectively adjusting thethrow of one die relatively to the other die.

These, other and further objects and advantages of the present invention will be clear from the description which follows and the drawings appended thereto, in which:

Fig. 1 is a perspective View of a .power press according' to my invention,` the parts being shown in the positions assumed by them when the apparatus is inopen or inoperative position.

Fig. 2 is a partial perspective view `of the power l press, the parts being shown in the positions assumed by them when pressing Ya fan'blade into shape.

Fig.. 3 is a horizontal section on the '-line -3-3 of Fig. 2.

Fig. 4 is a detail elevation of the air cylinders"v which operate the members ycarrying the'core and the dies by which a, sheet of metal is bent in'the power press to form the fan blade.

Fig. 5 is another detail elevation illustrating the core and the dies in initial open position.

Fig. 6 Vis a detail elevation of the rack and spring adjusting means for a die carrying channel.

Fig. 7 is a section on the line 1-1 ofV Fig.' 6.' Fig. 8 is a schematic View of the fluid air system for operating the power' press.

Fig. 9 is a detail front view of the core and its mounting elements;

Fig. 10 is a partial' perspective view showing the concave' die and the core used in a power press according tol my invention.

Fig. 1l is a section'across'hthe width of the fan blade manufactured in the power press of my invention.

Reierring now tothe'drawings and more particularly lto Fig. 11, I have illustrated there a hollow fan blade I0 which is'formed from sheet metal that is'bent over upon itself in the power plress, which is the subject of the within application."

The fan blade is formed with the hollow interior I2 andcomprises the surfaces 2i] and 24, which aremade pursuant tothe method of the said divisional application, extending between the edges 2,8 and 32, which latter is welded together to close it.

Y The core 34 and the dies`36 and 38 are made in accordance with the method which is the subjectmatter olf4 my said divisional application, to which reference is heremade.

Inl Figs; l et'seq.,jI` have illustrated in such detail a's will be necessary for an understanding of my invention, a power press in which the thus cast iron core 34 and cast dies 36 and 38'are mounted to .press from a sheet of metal a fanA blade of the selected size and cross sectional shape. Y,

In Fig'. 2,. the movable parts of the power press 83 are illustrated in their closed position, bending andk pressing the lsheet metal into the form of the Selected fan blade. In Fig. 1, the core 34 is illustrated in raised position, that is withdrawn from between the dies 36 and 38.

Referring now to Fig. 8 (which is a schematic detail illustration')`, the dies 3,6 and 38 have been separated 'and the core 34 withdrawn from between them, th'us arranging the power press in condition to commence the blade forming operations from a sheet of metal. The sheet of metal, from which'the fan blade is to be formed, is first bent into a'substantial V or` U-shape and placed between the open dies 36 and 38 (Fig. 5).

The thus initially bent sheet of metal is preferably heated so thatit may be, 'more readily bent and pressed into shape on the core 34"between the dies 35 and 38 to form a hollow blade suchr as illustrated in Fig. 1l by the power press B8 the'operation of which will now be described.

It will be understood of course,A that the edge 32"(Fig. 11), which is formed bythe abutting surfaces 20 and `24; after the bladevispressed into shape in the power press, is welded together to, close it and the thus welded edgeI then ground to form a uniform and flat surface.

TheA powerl press 88 is preferably' fluid operated as by compressed air supplied from a suitable reservoir or tank (not illustrated) which is connected by means of the pipe line or conduit to the valve ||2, which latter is operated, as I shall describe, to direct air to the particular pistons of the power press.

The valve ||2 is designed to direct air frontl p the air supply into the core operating cylinder |36 by means of the dash pot |32 and at the proper time to the die operating cylinder |46 to bring the core 34 between the dies 36 and 38 and close the dies on the` sheet metal and the core. as will be described in further detail, and to concurrently exhaust any air remaining in the other sides of these cylinders from a preceding operation through the exhaust pipe |20 (Fig. 8).

The valve ||2 has three diierent positions, the closed position, at which theH core 34 is brought between the thereupon closed dies 36 and 38 as illustrated in Fig. 2, the opened position at which the core is raised from between the separated dies (as illustrated in Fig. 1 and as also shown in Fig. 5) and a neutral position between the opened and closed positions at which air is not directed into any of the cylinders.

It will be of course understood that means other than air may be used to operate the movable elements of the power press here concerned with and that the specific details shown `are for purposes of illustration only.

In order to operate my apparatus, after inserting the V-shaped sheet metal between the separated dies 36 and 38, the handle |22 is turned in clockwise direction from the neutral position illustrated by dotted lines in Fig. 8 to the position illustrated by the unbroken lines, (as viewed in Fig. 8) until the stop lug |24 on the handle is brought into engagement with the stop member |26 on the body of the valve. The ports of the valve ||2 are thus fixed in proper alignment so that air flows through the pipe line or conduit |28 leading to the pipe line or conduit |30, Air is thus directed into the oil dash pot |32, which is used to retard or slow down the movement of the piston |34, which operates in the cylinder |36 and which as will be described moves the core 34 from the position illustrated in Fig. 1 (and the position illustrated in Fig. 5) into the blade forming position illustrated in Fig. 2. Air is directed into the dash pot |32 which forces oil therein thru the conduit |38 to move the plunger |34 outward in the cylinder |36. Air remaining from a preceding operation on the other side of that plunger is exhausted through the conduit |40, the conduit |42, valve ||2 and the exhaust pipe |20.

The piston |34 is connected to the core 34 by a linkage that I shall describe in greater detail and moves the core 34 into position against the sheet of metal from which the fan blade is to be formed. It will of course be understood that the operation of the core and the dies must be synchronously timed so that the core is rst brought home in the hollow of the V-shaped sheet metal and held there against it before the dies are brought together to form the fan blade.

In order to provide for such sequential operation, I provide in the conduit |44 leading to the cylinder |46, the piston |48 of which, as shall be described, brings together the dies 36 and 38, the check valve |50. This check valve |50 ordinarily prevents the flow of air from the conduit |28 into the die operating cylinder |46 although air is directed, as heretofore pointed out into the oil dash pot |32 for actuating core operating cylinder |36.

The check valve is provided with a handle |52 which is positioned in the path of movement of the arm |54 secured on one of the levers |56. which form a part of the linkage by means of which the core 34 is operatively lowered and raised, the operation of which I shall describe in greater detail.

As the lever |56 moves down under the in- Aiiuence of the piston |34, when the core 34 is brought home against the sheet metal positioned between the dies 36 and 38, the arm |54 is so mounted relatively to the other elements of the connecting linkage so that it engages the handle |52 to open the check valve |50. Thus when the core 34 is properly positioned and held in the hollow of the V-shaped metal, air is then directed into the die operating cylinder |46 to bring the dies together and form the hollow properly shaped fan blade.

Air remaining from a preceding operation is concurrently forced out by the piston |48 through the conduit |58, the conduit |42, valve |2 and exhaust pipe |20.

The valve I2 is held closed until the operator has shaped the sheet metal into the desired fan blade form, after which, the handle |22 is swung in a counter-clockwise direction (as viewed in Fig. 8) from the position illustrated by the unbroken lines into the valve opened position, illustrated by dotted lines, whereat the stop lug |21 is brought into engagement with the other side of the stop member |26.

The ports of the valve I |2 are, in this position, arranged to shut olf air flowing from the air supply ||0 through the conduit |28 and thus those sides of the dash pot |32 and die operating cylinder |46 which move the respective pistons to cause the core 34 to be raised and the dies 36 and 38 separated. The conduits |30, |44 and |28 are however connected to the exhaust pipe |20 so that air remaining in these clyinders on the other side of the pistons will concurrently be expelled from them as the pistons are moved to the other end of the respective cylinders.

In this position of the valve ||2, air is now directed from the air supply into the conduit |42 and from there into the cylinder |46 to separate the dies 36 and 38. As these dies are opened air is directed into the core operating cylinder |36 which raises the core 34.

Air remaining cn the other side of the respective pistons is concurrently exhausted through the conduit |28 and the exhaust pipe |20. As the lever |56 is raised, the arm |54 is brought out of engagement with the handle |32 thereby permitting the check valve |50 to return to its normal closed position so that further discharge of air from cylinder |46 is prevented. .Y

I shall now describe the linkage whereby the core 34 is lowered and raised and the dies 36 and 38 brought together and separated by the uid (air) so directed into the cylinders |32 and |46.

The power press 88 is mounted on any suitable means such as the table like support which consists of the legs |60 and cross braces |62.

On each side of the press, extending from one end to the other end, I provide the transverse channel beams |64 which carry the operating elements of the press.

Adjacent one end of the power press, I provide the spaced uprights |66 and |68 between which the dash pot |32 is carried and rigidly held in position by any suitable means, the piping or conduits |30 being rigid and piping or conduit |38, being flexible. The core operating cylinder |36 is mounted as by the nuts and bolts on these uprights, as is the die operating cylinder |46, the latter as by the nuts and lbolts |12. These uprights |66 and |68 are secured to the end cross piece |14 mounted on the side channels |64 in any suitable manner.

Intermediate the power press, I provide another pair of longer uprights |16 and |18 on which the core 34 carrying linkage is mounted and which uprights are secured to the cross piece |80, mounted between the channels |64, by any suitable means as by the lbracket |82.

In this connection, it should be recognized that the core 34 must be given a composite movement, that is, it must be swung from the angular position indicated in Fig. 1 to the rear over the open dies 36 and 38 into a substantially vertical position between them and concurrently lowered from the top of the power press into position between the open dies arranged there beneath, which latter position is illustrated in Fig. 2. Conversely the core must be raised and swung forward of the apparatus from the position illustrated in Fig. 2 to the position illustrated in Fig. 1, after the blade is pressed into shape.

In order to provide extra spring tension on lever |90, by means of an additional spring |99, I preferably secure to each upright |66 and |68, an arm |83 and |85, the outer ends of which are provided with the apertures |81. At the upper end of the intermediate uprights I 16 and |18, I secure the cross rod |89 on which is held one end of the arm |9|, the other end of the arm |9| being provided with the openings |93.

In the apertures |81 and the openings |93, I mount the supporting cross piece |95, the position of which may be thereby selectively fixed. In the apertures |81, I mount the cross rod |91, to which one end of the spring |99 is secured, the other end of the spring |99 :being secured to the lever |56.

I shall now describe the linkage by means of which the above described movement of the core 34 is accomplished.

On the outside of each intermediate upright |16 and |18, I fix an end 20| and 203 of a compression spring |84 and |86. The other end of each spring is connected to the corresponding pivot |83 on the lever |90 and the corresponding pivot |92 on the lever |56. Thus the pivots |88 and |92 move downward underl the resistance of springs |84 and |86 which are compressed under the corresponding movement of the piston |34. The outer ends of the operating levers |56 and |90 are also free and carry the shaft |94 from which the core 34 is suspended by the arms |96 and |98.

The levers |56 and |90 are pivotally xed intermediate their ends to the blocks k|51 and |59 secured to and extending to the rear of the end 'uprights |16 and |18.

The upper ends of the arms |96 and |98 are mounted on the shaft |94 (see Fig. 9.) by any Vsuitable means such as the clamps 200 and 202 and the lower ends of the arms are secured to the lugs 204 and 206 extending from the sides of the core 34. These lugs serve the purpose of cooperating with the fingers 208 and l2|0 projecting .from the sides of the die 36 (see Fig. 10) to properlyposition the core against the metal plate and Within the dies 36 and 38 when they are brought together.

When these dies are brought together after the core has been lowered between them, the fingers 208 and 2|8 are brought into sliding engagement with the lugs 204 and 206 to pull the die down into proper position against the V-shaped plate in the event it was not sufficiently lowered into position by the linkage thereby providing a means of always insuring that the core is brought home against the sheet of metal as it is being pressed into shape.

Mounted between the intermediate uprights |16 and |18 on the pivot 2|2, I provide the links 2| 4 and 256, which are rigidly secured to each other by the spacer 2 |8. The lower ends of these links are secured to the shaft 220 on which the upper ends of the links 222 and 224 are also mounted. The lower ends of the links 222 and 224 are connected to the shaft 226, which is secured to the levers |56 and 90.

The outer end of the piston |34 is mounted on the shaft or knuckle 220, which is moved outward from the piston illustrated in Fig. 1 to the position illustrated in Fig. 2 when air is directed into the dash pot |32 to move the piston |34.

This outward movement of the shaft or knuckle 220 causes the links 2|4 and 2|6 to rotate in a counter-clockwise direction, as viewed in Figs, 1 and 2, which in turn causes the links 222 and 224 to move in a clockwise direction, as viewed in Figs. 1 and 2.

Since the links 222 and 224 are connected to the levers |56 and |90 by means of the shaft 226, the corresponding ends of the levers, which are free to move, are forced downward thus lowering the core 34. This compresses the springs |84 and |86, the pivoted ends |88 and |92 of which are also free to move. By this arrangement, the core 34 is lowered into position between the dies 36 and 38.

When the piston |34 is retracted by means of properly directing air into the cylinder |36, as previously described, the shaft or knuckle 220 is pulled inwardly by the piston |34 causing the links 222 and 224 to rotate in a counter-clockwise direction (as viewed in Figs. 1 and 2) to raise the core 34 from between the dies 36 and 38.

As pointed out above, the core 34 after it is raised from between the dies 36 and 38, which motion must be substantially vertical, is then swung about the moving pivots |88 and |92 into the position illustrated in Fig. 1. This concurrent motion is accomplished by the linkage which I shall now described.

Extending out from the upright |18 and secured thereto, I provide the platelike member 228 on which is mounted the stop 230. I mount, as by the pivot 232, the link 234 to this plate-like member 228.

Secured to the link 234 by the pivot 236, I provide another link 238 to which the arm 240 is also secured by means of the pivot 242.

The arm 240 is mounted on ythe core carrying shaft |94 as by the clamps 244 (see Fig. 9).

Thus, when the core 34 is raised from the posivtion illustrated in Fig. 2 to the position illustrated in Fig. l, the link 234 is brought into engagement with the stop 230 thereby holding the link 234 in the thus stopped position. This causes the link 238 to rotate about the pivot 236 in a counter-clockwise direction and the arm 240 about the pivot 242 also in a counter-clockwise direction to bring the core 34 into the position yillustrated 'in Fig. 1.

When the core 34 is lowered, the linkage formed by the links 234 and 238 straightens out (that is the links 234 and 238 are brought into alignment) to permit the core 34 to be lowered substantially vertically between the dies 36 and 38.

As previously pointed out, when the core 34 is lowered into position between the dies 36 and 38, the valve |50 is opened and air is directed into the cylinder |46 to close the dies on the core. I shall now describe the linkage whereby this operation is accomplished.

The die 36 is secured to the face 244 of the channel member as by means of the lugs |04 and |06 and bolts 248 and 249. In order to provide a simple means for securing diierent dies to the face 244 of the channel member |00, I provide in the face 244 a plurality of spaced apertures 250 so that different sizes of dies may be accommodated.

The die 38 is likewise secured to the face 252 of nected to the countershaft 214 at the center? thereof between the collars 216.

Between each pair of spaced arms 212, I connect at one end thereof the arms 218 and 280 to the countershaft 214 and at their other ends to the pivot shaft 282 extending in the rear of the face 244 of the channel |00.

As pointed out, the dies 36 and 38 are connected together by the ngers through which the pivot |01 extends.

The channel |02, on which the die 38 is mounted is pivoted to the supports 284 and 285 by means of the cross shaft 286, which supports 284 and 285 are mounted on the end cross piece 288, which rests in position on the channels |64. The other end member |14 is rigidly fixed to channels |64.

From the position illustrated inFig. l, when the piston |48 is moved downwardly, the countershaft 214 is pushed in front of it to rotate the connecting arms 212 in a clockwise direction, as viewed in Figs. 1 and 2 causing the connecting arms 218 and 280 to move in a counter-clockwise direction on the pivot shaft 282, thus straightening out the linkage formed by the connecting arms 212 and arms 218 and 280 (as illustrated in Fig. 2)

This causes the channels |00 and |02 to rotate toward each other about the pivot |01 to bring the dies together on the core and the V- shaped plate and form the fan blade.

Upon reversing the air in the cylinder |46, the piston |48 is retracted pulling the dies apart by the reverse action of the connecting armsand the pivots and permitting the core to be withdrawn and the formed fan blade removed.

If desired, cooling fluid may be directed past the dies 36 and 38 in the event that the sheet metal plate from which the fan blade is formed has been heated and it is sought to cool both the dies and the formed fan blade more rapidly than by air.

Referring now to Fig. 6, I have illustrated there a spring arrangement whereby the weight of each jaw comprising the blade forming die is counterbalanced.

Resting on the longitudinal channels |64 at each side of the power press on the interior thereof, as will be described, I mount the racks 290 and 292, which are disposed at an angle to the vertical and extend toward eac-h other at the lower part thereof.

At each side of the power press in aligned notches of the racks 290, I mount a positioning rod 294 and at each side of the press in aligned notches oi the racks 292, I mount a positioning rod 296.

This construction is illustrated in detail in Figs. 6, '1 and 8, reference also being made to Figs. 1 and 2. The racks 290 and 292 are carried respectively by the plates 295 and 291.

Each plate 291v on which each rack 290 is mounted is slidable from the front to the rear of the machine and vice Versa on the side channel |64, at each side of the press, and is each xedly secured to a crosshead 330 and a crosshead 332.

In Figs. 6, 7 and' 8 only one side of the press is illustrated, and a, plate 295 and a plate291 and a corresponding rack 290 and a rack 292 is provided on each side of the power press with a rod 300 and a rod 306 being provided at the center of the press. A plate 295 is slidable reciprocably at each side of the press on the side channels |64 and is xed to the cross channel 288.

In Fig. 6 and Fig. 7 only one set of racks 290 and one spring 302 are illustrated, it being understood that the substantially vertical rod 306 is pivotally mounted to its corresponding channel |02 in the same manner that the substantially vertical rod 300 is pivotally mounted to its corresponding channel |00.

n Referring now to Figs. 6 and '1, the positioning rods 294 are secured at each end thereof to, the channel 293 so that they may be adjustably placed in aligned notches of the racks 290, the positioning rods 296 carried by a similar cross channel (not illustrated) being mounted inraligned notches of the rack 292 to control the die 38 in the same manner as the die 36 is controlled.

The substantially vertical rod 300 carries about it the compression spring 302 which is compressed between the washer 303, carried by the rod 300 and the channel 293, in which the lower end Aof the rod 300 may reciprocate. It will be understood that the vertical rod 306 is similarly mounted between the channel |02 and a, channel similar to 293.

By arranging the positioning rods 294 and 296 in selected notches of the racks 290 and 292, the spring compression may be adjusted to accommodate the weight of a particular die, the size of which may be varied in practice for a particular fan blade design.

The springs 302 and 308 serve the purpose of retaining the dies `36 and 38 in open position, which would otherwise close under the weight of these dies which would form a closing movement about their pivots.

It may be necessary to adjust the relative position of the die carrying channels |00 and |02 to thereby accommodate dies of different sizes and to adjust the amount of pinch imposed by the closed dies on the sheet of metal between them and the core. This is accomplished by adjusting the position of the cross- Wise end channel 288, which as pointed out, is reciprocable on the side channels |64. A

In order to provide for this adjustment, I pass through thecnd pieces |14, 288, crossheads 9 330 and 332, the longitudinal bolts or rods 3|0, 3|2,3|4and3|6.

In this connection, it should be recognized that the channel is secured to the stationary end channel |14 by means of the members 212 and members 218 and 280 and that the channel |02 is secured to the slidable end channel 288 by means of the ngers 284 and 285. Thus, by bringing the end channels |14 and 288 closer together, the channels |00 and |02 and so the corresponding dies 36 and 38 will be brought closer together about the pivot |01, which latter would then move downward, as viewed in Fig. 6. Conversely, separating the end channels |14 and 288 more will further separate the channels |00 and |02 and their dies 36 and 28, the pivot |01 then being moved upward as viewed in Fig. 6.

In order to accomplish this, I secure on the bolts or rods 3|0 and 3|2, the nuts 3|8 and 320 which are held together by the rod 322. I also secure on the bolts or rods 3|4 and 3|6, the nuts 324 and 326 which nuts are secured together by the rod 328.

In order to provide for greater rigidity, the bolts or rods pass through the crossheads 330 and 332, which are mounted on the plates 291 slidable on the side channels |64 substantially at the center of the power press, the bolts serving as guides for the movement of the crossheads. The channel member |00 is also secured to the bars 33| of the crossheads by means of the pivots 333, which latter are extensions of the rod 282.

Against the member |14 at the face 266 thereof, I arrange on the rods or bolts the nuts 334.

Threaded on each rod or bolt at the end of the power press on the other side of the end piece |14, I provide nuts which are welded to sprocket wheels (not shown) and are engaged by the chain 336.

Mounted on the nut and sprocket wheel which is supported by the bolt or rod 3|4, I provide the handle 338, rotation of which in the proper direction will move the end piece 288 to the right or left as viewed in Figs. 10, 11 and 12 thus adjusting the relative positions of the dies 36 and 38 and the amount of pinch imposed by them.

On the other side of the end piece 288, I arrange on each rod or bolt 3|0, 3|2, 3|4 and 3|6, the nuts 340 thus providing a further means of moving the end piece 288 relative to the end piece |14, it being recognized that the end piece 288 is slidably mounted on the channel beams |64.

A preferably heated sheet of metal of proper size and in V-shape is inserted between the separated dies 36 and 38 and the power press operated to lower the core 34 into position between the bent parts of the V-shaped plate. When the core is thus lowered, the dies are brought against the sheet of metal which is forced around the core 34. This is accomplished as previously described, by operation of the handle |22.

After the blade is thus formed, the dies are separated and the core raised by proper operation of the handle |22. The hollow blade is carried as a sleeve around the core and ls removed therefrom at the sides thereof.

It will still further be recognized that I have provided a power press which utilizes the core and dies formed by the method illustrated and described in my divisional application to manufacture from a sheet of metal a hollow fan blade.

As obviously, many variations may be made in the method and embodiment of my invention which I have described, within the scope and spiritI of the invention, I do not intend to be limited to the exact details disclosed but intend to claim my invention as broadly as the scope of the claims and the state of the prior art allow.

I claim:

1. In a power press for pressing and bending a sheet of metal into the hollow fan blade. a frame, a pair of dies pivoted to each other mounted in the frame and normally separated to receive the sheet of metal therebetween, linkage connected to one of the dies for bringing together and separating the dies, uid operated means connected to the said linkage for operating the same, a core mounted on the frame and normally raised above the dies, second linkage connected to the core to impart to the core a compound motion whereby the core is lowered from normal position above the dies into position between the separated dies against a sheet of metal received therebetween and raised from said lowered position between the diesk to normal p0- sition, second iluid operated means connected to said second linkage for operating the same, and valve means for directing the uid to the second iluid operated means and to the first fluid operated means, said fluid arranged to be directed in sequence to the second iuid operated means to lower the core between the separated dies against the sheet of metal and then to the iirst nuid operated means to bring the dies together against the sheet of metal and the core to form the ian blade and thereafter to the rst fluid operated means to separate the dies and then to the second iluid operated means to raise the core to normal position.

2. In a power press for pressing and bending a sheet of metal into a hollow fan blade, a frame, a pair of separable blade forming dies pivoted to each other and mounted on the frame and means for counter-balancing the weight of each die about the pivot comprising a rack for each die, each rack having aligned notches, a positioning rod in aligned notches of each rack, a member pivoted to a die and a corresponding positioning rod and spring means on each member between the corresponding die and positioning rod.

WINFRED N. LURCOTT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 254,249 Vanstone Feb. 28, 1882 414,687 Dopp Nov. 12, 1889 1,058,775 Mciillop Apr. 15, 1913 1,109,522 Fraser Sept. 1, 1914 1,127,109 Tarpenning Feb. 2, 1915 1,138,639 Dietrich May 11, 1915 1,258,892 Griiin Mar. 12, 1918 1,267,368 Bowles May 28, 1918 1,497,857 Krump June 17, 1924 1,701,250 Young Feb. 5, 1929 1,707,463 Ford Apr. 2, 1929 1,880,454 Klocke Oct. 4, 1932 2,373,163 Cailloux Apr. 10, 1945 FOREIGN PATENTS Number Country Date 15,147 Great Britain Oct. 26, 1915 770,908 France July 9, 1934 346,455 Germany Jan. 2, 1922 

